SRM clutch

[BrianS]

Thanks again for the help and advice chaps!
Following an enforced break I realised that I can drive and ride again from Tuesday so put my mind to re-assembling Flash today.
I have just put the primary chain cover back on after having adjusted the clutch and, unfortunately, the crankcase threads for one of the bolts feels like it's about to strip. 
The threaded section goes right through to the outside world so I can fit a longer bolt that will catch on good threads but, where to find such an odd Imperial beasty? 
The original is a 1/4" x 1.3/4" x 20 tpi Allen/Socket/Cap headed screw that is not threaded along its whole length.
Ideally I would like to find a bolt at least quarter of an inch longer. Anyone got such a thing or can advise where I might get one please?
Also, I haven't sourced SAE20 oil as recommended to use by SRM. Could I use Fuchs Silkolene Super 4 10W-40 semi-synthetic oil which is suitable for wet clutches instead (I use it in my TTR250).
Brian
PS I bet we get a fortnight of rain starting Tuesday :-(

[JulianS]

Its just a 1/4 x 20 tpi Whitworth (BSW) thread.

https://www.ebay.co.uk/itm/1-4-X-1-3-4-UNC-BSW-CAP-HEAD-SOCKET-SCREW-BOLTS-STAINLESS-UCB11-25-14/253164497210?hash=item3af1c7a93a:g:Ozk

[BrianS]

Thanks Julian - I will get a pack ordered!
Regarding the oil, I emailed Gary at SRM and he replied:
"Hello Brian,
I think the 10w-40 will be fine for your clutch, its only 1/3 pint, approx 190cc/ml.
Hope that you manage to get some miles in before the weather gets worse.
Regards Gary"
So I should be good to go for tomorrow ;-)

[BrianS]

I see it's been a little while since my last post so here's the update.

After taking off the cover and tightening the clutch springs (I hadn't realised at that point that I could do it without taking off the cover!) I put it back together and took the A10 out for a test run and the clutch slip was worse than before 

I tightened the clutch springs through the inspection window on the cover (why hadn't I thought of doing this before!) but it made no difference.

Despite checking (or so I thought I had!), I believe that I had adjusted the SRM "pusher" incorrectly and reminded myself of John's (chaterlea25) advice from 11th August:
"A clutch slippage problem can arise when the SRM "pusher" butts up against the end of the gearbox mainshaft (or nut)
(this can happen if the pushrod was cut a bit short) in this case  pushrod free play may be still "look OK" but there is no play at the clutch end "

I have slackened the pusher off and re-assembled everything and I appear to have no slippage. If (whilst riding) I pull in the clutch in top gear, rev the engine and drop the clutch the revs immediately drop so I am thinking I am OK - fingers crossed.  Thanks John!!!!

A couple of things arose.

Firstly, I tried the Hylomar on both sides of the cover gasket and greasing the engine side but it didn't work for me. When I took the cover off, the gasket actually separated along most of its length leaving half on the engine side and the other half on the cover. Maybe I didn't put enough grease on the engine side? Anyways up, I might just Hylomar the cover side next time. I think I have got away with re-using the old gasket this time around but a leak check this morning will tell me having put clean newspaper underneath after my test ride yesterday.

Secondly, I bought a pack of 2" bolts from eBay, https://www.ebay.co.uk/itm/1-4-X-2-UNC-BSW-CAP-HEAD-SOCKET-SCREW-BOLTS-UCB11-25-16/112229104834?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649, and used one to replace a damaged bolt and the length was perfect - see photo below to compare old and new. the end of the bolt just shows through the engine side casing so hasn't got spare thread hanging out to get rusty. Thanks for the tip Julian!

Shame the weather has turned as I am a fair weather rider so further "testing" is on hold until the sun re-appears.

[RDfella]

Kicking the bike over with clutch lever pulled in before starting is as natural to me as breathing. I ALWAYS do it. And most of my bikes (certainly all the BSA's) need it. You can feel it free off. Beats smashing first gear when going to move off. And in my case it's not caused by oil, because I don't use oil in my primary chaincases, I merely oil the chain occasionally and, around every 3,000 miles or so, take it off and boil in grease. That's a choice I made many years ago when I was having grief with my Triton. Remove the primary cover, strip clutch and wash plates in petrol, re-assemble, add oil and use. And two days later the same, because the plates slipped just sufficiently on kickstarting to prevent 'striking a light'. OK, it was a high compression motor with 3134 cams etc, but who wants a bike that won't start? I've had to get push starts on that thing just to get home. That, coupled with an alternator which couldn't keep up with the lights and a frame I didn't like meant I sold that bike within a year.
Why do you think BSA went to the trouble of a fully covered clutch on some models? It is a dry clutch running in a wet environment. If it was meant to run in oil the plates would either be cork or bronze.

[BrianS]

Unfortunately, my SRM clutch started to slip again so I stripped it right out to check the plates and they all look OK although a bit blackened - see attached photo. I hope they were OK to re-use as a new set is over £130 and these have done less than 1,200 miles.

I also attach a photo showing the pushrod and wonder if maybe I didn't cut enough off on the original installation?

I rebuilt the clutch with just a tad over the quarter turn of free play on the centre adjusting nut and all seemed fine on a test ride.

Yesterday was our Club's annual Dartmoor run and my A10 covered the 100 miles without any clutch slip including carrying a pillion passenger for the last 40 miles whose own bike had broken down.

I parked the A10 up whilst the awards ceremony etc took place so it had pretty much cooled down by the time I came to leave. I hadn't gone far and it was apparent that the clutch had started to slip again quite badly.

I hope to be getting the clutch cover off again later to see what's happening but what should I be looking for - what are the most likely mistakes that I could have made on the last clutch rebuild?

Brian

PS Question - is the clutch supposed to run dry (like mine seems to be) and the crankcase oil confine itself to lubing the primary chain?

[BrianS]

Replaced my Triumph 4 spring type clutch which has been on the bike for about 50 years with a new SRM one.

The new clutch has been problematic.  Have tried various grades of oil and get about 600 miles or so before it starts to slip.  Have just adjusted it again and note I have to screw the clutch nuts in much more than SRM suggests. 

Will be interesting to see if my clutch has bedded in or starts to slip again.  i wonder if I have the wrong cups and springs or perhaps the plates have been contaminated.  Time will tell.

Thinking of putting the old plates back in with their cups and springs.

Just my experience.

Did you get your SRM clutch sorted Keith and, if so, what was the cause of the re-occurrence of the slipping please?  I have the same symptoms unfortunately 

[duTch]

 

.........PS Question - is the clutch supposed to run dry (like mine seems to be) and the crankcase oil confine itself to lubing the primary chain?

 yeah sumthin like that...now where was I..... sidetracked with a anti-something with the offspring (conspiracy theories)......Brian, sometimes you just need to fufufufufu with these thing s until you work it out....

[RogerSB]

Hi Brian, sorry to hear your still struggling with your clutch.
When I fitted my SRM 4-spring, in 2017, I made up an instruction sheet (based on SRMs fitting instructions) for myself to follow and for my future reference and thought it may be of some help to you.
Bear in mind what I bought from SRM was a complete SRM clutch assembly (so there's no mix of parts).
Also I'm using 8 fl oz (225 cc) straight monograde SAE 20 in the chaincase, which is more than Gary at SRM recommends for their clutch and after 2 years, more often riding two up, I don't get any slip.
If my bike is left unused for any length of time, which isn't very often, the clutch plates can stick together. I try to make a point of riding, or at least moving and starting, my bike every couple of weeks - both summer and winter. However, there are times when that's not possible or just doesn't get done. So, every time I put my bike to bed, to counteract the chance of the plates sticking together, I pull the clutch lever in and slip a pre-adjusted cable tie (kept handy for just that purpose) over the lever and the handlebar grip to disengage the clutch 'just enough' so that the plates are held separated.  Otherwise I have done, as RDfella always does, pull in the clutch lever to make sure the plates are free before kicking it over.

[BrianS]

What an excellent idea Roger - the SRM instructions are a tad all over the place!  Is there a second page to yours please?

I think I know what I did wrong to cause my clutch to slip.  I followed what I thought were the A10 instructions and only adjusted the centre fixing to a quarter of a turn when Gary tells me it should have been a full turn of free play   

I followed section 9 of the instructions instead of section 7 - see here http://www.shop.srmclassicbikes.com/sites/default/files/downloads/SRM-PP-A4.pdf

Also he confirms the clutch plates should not be run dry. However, by using the SRM recommended 190cc no oil seems to get on my plates. So I am going to put enough oil in to overflow at the level screw. Will that be 225cc? I will check ;-)

[RogerSB]

What an excellent idea Roger - the SRM instructions are a tad all over the place!  Is there a second page to yours please?

I think I know what I did wrong to cause my clutch to slip.  I followed what I thought were the A10 instructions and only adjusted the centre fixing to a quarter of a turn when Gary tells me it should have been a full turn of free play   

I followed section 9 of the instructions instead of section 7 - see here http://www.shop.srmclassicbikes.com/sites/default/files/downloads/SRM-PP-A4.pdf

Also he confirms the clutch plates should not be run dry. However, by using the SRM recommended 190cc no oil seems to get on my plates. So I am going to put enough oil in to overflow at the level screw. Will that be 225cc? I will check ;-)

Hi Brian, I'm pleased it may be of some help to you. Attached is what I got from SRM with my clutch, so you can see why I made up my own to follow.
There is only one page Brian, just covers the fitting and the push rod/pusher adjustment.
The important thing is to make sure the adjusting arm on gearbox is at 90 degrees to the pushrod when control lever is pulled in (clutch disengaged). About half way in to fully in is the best place, so it leaves some room for adjustment later. When the lever is released fully (so clutch is engaged) and with the pushrod firmly up against the pusher in the pressure plate you need a little 'rocking' free play between the end of the pushrod at the gearbox end and the adjusting lever's ball bearing. Secondary adjustment, if needed, can be made to the pusher's adjustment on the pressure plate and finally at the handlebar lever. I personally like about 1/8" free play at the handlebar lever. I only ever need to pull the lever in half way (if that) to disengage the clutch.

(Edit): 225 cc is BSA's recommended amount and at that point it should start to overflow the drain plug's tube. This, of course, will be dependant on the metal washers, fibre washers, etc. fitted to the drain plug (to stop it leaking), which will obviously adjust the level of the tube inside.

Good luck.

[RoyC]

If my bike is left unused for any length of time, which isn't very often, the clutch plates can stick together.  So, every time I put my bike to bed, to counteract the chance of the plates sticking together, I pull the clutch lever in and slip a pre-adjusted cable tie (kept handy for just that purpose) over the lever and the handlebar grip to disengage the clutch 'just enough' so that the plates are held separated.  Otherwise I have done, as RDfella always does, pull in the clutch lever to make sure the plates are free before kicking it over.

I do that with a strip of velcro but the plates still stick together.
I have to kick it over a couple of times with the lever pulled in until the clutch plates separate. It's a PITA.
I also use straight mono-grade SAE 20 oil.

[RogerSB]

I do that with a strip of velcro but the plates still stick together.
I have to kick it over a couple of times with the lever pulled in until the clutch plates separate. It's a PITA.
I also use straight mono-grade SAE 20 oil.

Hi Roy, To adjust the cable tie in the right place I originally fitted it so that I could depress the kick start without it turning the engine over (i.e. so clutch plates are disengaged). Velcro may be a bit hit and miss each time unless you keep it stuck together in the same place so you have the same lever adjustment every time.

[BrianS]

It was instruction 13 that caused my problem Roger 

For the A10 the adjusting screw needs to be one full turn out according to Gary who told me "adjustment at 1/4 turn would not have accounted for expanding friction plates when engine got hot, could be why they slipped, hence the one full turn on centre adjuster for clearance."

[BrianS]

As I have said in previous posts SRM recommend 190cc of oil in the chain case and no more.   

ELLIS

I mentioned in my recent email to SRM's Gary that when I used 190cc of oil it wasn't wetting the clutch and asked if I should use the BSA recommended 225cc instead. He replied "There is an oil level screw, look on inside of outer cover and you will see a cutaway where the screw come through to gasket face, that will be the level screw, fit cover, leave that screw out, fill until oil comes out of the hole, then fit screw." so SRM aren't quite so dead set on the 190ccs after all.